Various infections such as bacterial, viral, fungal, and parasitic infectious diseases are playing a pivotal role in causing minor complications to serious threat to mankind. Especially viral infections like HIV, malaria, dengue, hepatitis, and COVID-19 are very dangerous and difficult to treat. Nature has long been seen with materials that can be used to combat illnesses and treat diseases. The need of the hour is to explore new medications and novel targets to treat infected people from natural sources. Bioactives and plant extracts obtained from natural products are enriched with a lot of potential antiviral medication candidates. Furthermore, phytomedicines and phytotherapy are gaining attention as they are economical and safe alternatives to other treatments. The current chapter deals with the utility of natural products in infectious diseases such as HIV, malaria, dengue, hepatitis, and COVID-19. © 2023 Elsevier Inc. All rights reserved.